Chapter 3 Authentication for FortiOS 5.0 : Agent-based FSSO : Introduction to agent-based FSSO : FSSO security issues
  
FSSO security issues
When the different components of FSSO are communicating there are some inherent security features.
FSSO installation requires an account with network admin privileges. The security inherent in these types of accounts helps ensure access to FSSO configurations is not tampered with.
User passwords are never sent between FSSO components. The information that is sent is information to identify a user including the username, group or groups, and IP address.
NTLM uses base-64 encoded packets, and uses a unique randomly generated challenge nonce to avoid sending user information and password between the client and the server. For more information on NTLM, see “FSSO NTLM authentication support”.